Hi @huygen, it seems like indeed requests to 188.8.131.52 come through, probably only DNS requests are filtered.
Now, if you mention that the "dig" command started working after adding your Mac's DNS, that's great. It seems your remanining issue is only related to Bundler, and not to any DNS resolution.
It seems to be cloning from a local repository with this command (I removed the --quiet parameter):
git clone --no-checkout "/opt/bitnami/apps/redmine/htdocs/vendor/bundle/ruby/2.3.0/cache/bundler/git/rich-50774502e3893a04be60fd735c8f2c96bc68acea" "/opt/bitnami/apps/redmine/htdocs/vendor/bundle/ruby/2.3.0/bundler/gems/rich-93d1dd9526e1"
We were able to reproduce this issue in the Redmine VM when installing the WYSIWYG editor, but with the latest version of the Redmine VM, 3.6.4-3.
Could it be possible you upgraded to Redmine 3.6.4-3? There is a known version with Git in that version cloning local repositories.
In order to fix that issue, please run these commands:
sudo ln -sf /opt/bitnami/git/bin/.origin/git /opt/bitnami/git/libexec/git-core/git-receive-pack
sudo ln -sf /opt/bitnami/git/bin/.origin/git /opt/bitnami/git/libexec/git-core/git-shell
sudo ln -sf /opt/bitnami/git/bin/.origin/git /opt/bitnami/git/libexec/git-core/git-upload-archive
sudo ln -sf /opt/bitnami/git/bin/.origin/git /opt/bitnami/git/libexec/git-core/git-upload-pack
After that, we were able to get past that error.